Mozilla developers identified and fixed several memory safety bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these bugs showed evidence of memory corruption under certain circumstances, and we presume that with enough effort at least some of these could be exploited to run arbitrary code.

Mozilla has released updates to some of their applications in order to correct some critical security issues. It is recommended to upgrade as soon as possible to the versions below, should you be using any of them: Firefox 20.0 Firefox ESR 17.0.5 Thunderbird 17.0.5 Thunderbird ESR 17.0.5 SeaMonkey 2.17

A weakness and multiple vulnerabilities have been reported in [Mozilla Firefox], Thunderbird and SeaMonkey, which can be exploited by malicious people to disclose potentially sensitive information, conduct spoofing attacks, bypass certain security restrictions, and compromise a user’s system.

The weakness and the vulnerabilities are reported in [Firefox versions prior to 19,] Thunderbird versions prior to 17.0.3 and SeaMonkey versions prior to 2.16.

Firefox 19 also contains their all new built-in PDF reader, which means that both Chrome and Firefox now has built in PDF readers. Those wanting to secure themselves from last week’s Adobe Acrobat Reader vulnerability could therefore choose Firefox as the alternative as well.